Spray dispensing is generally achieved by delivering a liquid product to a nozzle under pressure induced, e.g., by a pump, pressurized gas, or a collapsible wall container. Each of these dispensing systems have advantages and disadvantages that have made them more or less suitable for a wide variety of products. The thinner and less viscous the product, however, the easier it is to spray utilizing such pressure operated systems. The thicker and more viscous the product, conversely, the harder it is to spray utilizing such systems. Semi-liquid cream or like products, such as gels, thickened emulsions, and the like; products having high tackiness, tenaciousness or cohesiveness; or products having a very high solids content, are particularly difficult to spray through a nozzle utilizing conventional pump, pressurized gas, or collapsible wall dispensing systems.
Finger and trigger pumps as well as squeeze bottles, for example, are generally incapable of providing sufficient operating pressures for spraying thick cream-like products from nozzles and particularly for spraying products having a viscosity of 25 to 50 centipoise or higher. Gas operated systems are, of course, capable of supplying higher nozzle pressures but gas operated systems are prone to other problems, especially in inexpensive consumer product dispensing systems, including problems in providing clean start and stop action and a uniform metered spray especially with thick, cohesive products.
In spray product dispensing, whether in the industrial/commercial sector or in the consumer products sector, product safety is becoming increasingly recognized and even mandated as a prime requisite. Conversely economic/market pressures often require that such desirable increased safety be achieved without loss of convenience to the user and within a familiar product-package framework. Simultaneously, pressures exist to keep costs down, both in the immediate product costs to the consumer and in the overall environmental costs involved in providing and delivering the product.
In the area of anti-perspirant/deodorant products, for example, spray type products have been preferred by a large segment of the market, presumably in large part because of their "non-contact" mode of application; i.e., the product (as opposed to the package) is not susceptible to being touched by others prior to or between uses by a specific user as well as requiring only minimal user involvement with the target area.
Previous efforts to provide "non-contact" dispensing of products such as antiperspirant/deodorant products without fluorocarbon aerosols have generally involved attempted substitutions of other pressure sources for the dissolved pressurized aerosol gas, such as finger pumps, trigger pumps, squeeze bottles or substitution of other gas systems. Since these devices generally operate at lower pressures or lack long term uniformity of pressure, product formulations having decreased viscosities have generally been deemed necessary to permit successful spray application. Viscosity decreases, however, especially by use of increased solvent or volatile levels, whether aqueous or anhydrous, have generally not led to commercially satisfactory products, primarily because of increased problems of perceived wetness, coldness, runniness, and/or stickiness.
Similar problems of wetness, coldness and/or stickiness have been known to exist in non-spray antiperspirant products.
In the co-pending application Ser. No. 681,319 filed by David L. Shelton on Apr. 29, 1976 and assigned to The Procter & Gamble Company, now U.S. Pat. No. 4,083,956, issued Apr. 11, 1978 there are described certain highly stable anhydrous antiperspirant creams that are formulated with highly thixotropic cream vehicles containing particular concentrations of emollients and gelling agents which do not, in general, impart an undesirable, cold, wet or sticky sensation when applied to the skin, which exhibit minimal syneresis or bleeding of organic liquids from the thixotropic gel structure and which do not dry out or form unacceptable crusts upon prolonged exposure to the atmosphere. While the subject matter of the aforesaid Shelton application Ser. No. 681,319 was invented prior to the instant invention, the Shelton application did not contemplate the spray application of such a thickened cream product. The entire disclosure thereof, however, is hereby incorporated herein by reference as fully and completely as if physically reproduced hereat as exemplary of semi-liquid antiperspirant cream products which, in accordance with the methods and apparatus of the present invention we have discovered can be spray dispensed. However, it is also to be expressly understood that in its broader aspects our invention is not limited to spray dispensing of antiperspirant creams in general or as specifically described in the aforesaid Shelton application but is of general utility for spray dispensing of semi-liquid products as hereinelsewhere set forth.
In the antiperspirant field, however, the Shelton type formulations provide unique advantages when sprayed in accordance with the present methods and apparatus and form a unique combination therewith, enabling safe, convenient, aesthetically and environmentally satisfactory non-contact application of stable non-crusting antiperspirant products without wetness, coldness, stickiness or runnyness from a hand held and hand actuated dispenser.